S-Log w/ 1.31 Firmware PDF

[Doug Jensen]

Quote: Was wondering how those LUTS function when you alter the Slog itself. Do the LUTS alter with it?"

It is not possible to use a LUT (even if you own the CBK-RGB-1 upgrade) at the same time as you are using any Picture Profile - including a Picture Profile that uses S-LOG as the gamma option. Therefore, you cannot alter the S-LOG and use a LUT at the same time. Those two things are mutually exclusive.

Also, if you are using the CBK-RGB01 version of S-LOG, then you can't really change anything about it. Except for a little control over white balance, that version of S-LOG is always the same and can't be modified. Even if you use the "EI" form of S-LOG the actual output is always the same.

Quote: "Wish I could alter the LUT and record Slog unaltered, that might be more valuable. "

What's stopping you? You own the CBK-RGB01 upgrade, so can certainly alter a LUT using CVP File Editor and also record S-LOG unaltered. That's the whole point of LUTs. Technically, the F3 LUTs are more correctly called "MLUTs" or Monitor LUTs because they are intended for monitoring ONLY while the unaltered S-LOG is being recorded. You can make the LUT look however you want, and S-LOG will always be the same if you are using the CBK-RGB01 version of S-LOG. And as I said previously, if you are using the PP version of S-LOG, then you have no LUTs to worry about.

You're making it more complicated that it is. It's very simple, really. Once you get the new firmware and spend 30 minutes or so exploring it things will become more clear.

[Leonard Levy]

No I don't think I am. My concern about the LUTS is that they have such low chroma that they don't help much in getting a useable picture on set. It may say 709 but it looks very washed out. That is something that can't be altered by making your own LUT because its 1D not a 3D LUT. I'm just at the discovery point for working with SLog and so I may find they are very useful in the end. At this point I feel it was a waste of money. Alistair Chapman at NAB said he thought the LUTS were very important so I may yet change my mind. I don't want to spend more dough on an HDLink and don't know if that would solve the problem either. perhaps just cranking up the sat on the monitor. Despite many people here telling me that was a bad idea, Alistair thought it was fine.

I'll figure it out eventually. Thanks for the info about the new firmware though. I am curious what the point of making PP files from the SLog was though. Perhaps to create something that is a hybrid - more like C-Log on the Canon? Or just to dial in your color correction for the post guys ahead of time so they know what you want?

[Leonard Levy]

double post

[Doug Jensen]

I never use LUTs, and fortunately I don't have to work with clients who can't understand what S-LOG is supposed to look like. The way I see it, LUTs just get in the way of me doing my job simply for the sake of someone else having a prettier picture to look at on the monitor. . . a picture that is still inferior and not representative of what the final image will be in post. Screw 'em. I need to see what the camera is shooting at all times in the viewfinder. I can't do that with a LUT turned on.

I completely agree with you that none of the built-in LUTs looks very good, and I have no desire to jump through the hoops necessary to create my own. It is not easy to use CVP File Editor and I am not certain that a good-looking LUT is even possible.

Any client that isn't sophisticated enough to understand why S-LOG looks the way it looks, probably shouldn't be using S-LOG anyway. That's my opinion. I'm sure other people have a different philosophy. As always, since I started shooting 30 years ago, a little client education goes a long way to smoothing out the journey.

I stand by my opinion that shooting S-LOG and configuring the camera is very easy . . . it's what happens in post where the work begins. S-LOG only becomes hard when someone tries to use it in ways it was never intended to do. There aren't very many options with S-LOG and you pretty much give up most control over the camera except for exposure and focus -- so you either take it or leave it. Makes no sense to fight it.

[David C. Williams]

Leonard, if your after something more like Canon C300's C-Log just use Cinegamma curves. You will still have more dynamic range than C-Log and control of colour though PPs.

The C300 in C-Log has been measured as 2 stops short of the F3 in S-Log, and S-Log adds roughly 1.5 stops, ergo an F3 in REC709 still has more range than a C300.

[Leonard Levy]

thanks for the help guys. I've had plenty of conversations about whether your monitor matters and clients etc. We all have are ways of working and our different clients. I light pretty carefully and like a reasonable monitor as does my gaffer and most clients. Here I just wanted to find out how the new firmware will work. I'll figure it out.

[Ron Aerts]

Originally Posted by Doug Jensen

I never use LUTs, and fortunately I don't have to work with clients who can't understand what S-LOG is supposed to look like. .

Doug, do you think recording S-log 422 to an 8bit recorder has an advantage in post?

[Alister Chapman]

While we wait for Doug's answer... my own opinion is that while 8 bit, 422 can be used for S-Log, it is not something I would recommend. I'd rather use a cinegamma with 8 bit recording. 10 bit 422 S-log is another matter altogether, this is well worth using and works very well indeed.

What you have to consider is this. With 8 bit, you have 240 shades of grey from black to super white. Of the 256 bits available, 16 are used for sync, white is at 235 and super white 256 so black to 100% white is only 219. With Rec-709, standard gamma on an F3 you get about an 8 stop range, so each stop of exposure has about 30 shades of grey. When you go to S-Log, you now have around 13 stops of DR, so with 8 bit, now each stop only has 18 shades of grey. Potentially using 8 bit for S-Log, before you even start to grade, your image will be seriously degraded.

Now think about how you expose S-Log. Mid grey sits at 38% when you shoot. If you then grade this to Rec-709 for display on a normal TV then you are going to stretch the lower end of your image by approx 30%, so when you stretch your 18 steps of S-Log grey to get to Rec-709 you then end up with the equivalent of only around 12 shades of grey for each stop, that's less than half of what you would have if you had originally shot using Rec-709. I'm sure most of us have at some point seen banding on walls or the sky with standard gammas and 8 bit, just imagine what might happen if you effectively halve the number of grey shades you have.

By way of a contrast, just consider that 10 bit has 956 grey shades from black to super white. the first 64 bits are used for sync and other data, 100% white is bit 940 and super white 1019. So when shooting S-Log using 10 bit you have about 73 grey shades per stop, a four fold improvement over 8 bit S-Log so even after shooting S-Log and grading to Rec-709 there are still almost twice as many grey shades than if you had originally shot at 8 bit Rec-709.

This is a bit of an over simplification as during the grading process, if your workflow is fully optimised you would be grading from 8 bit to 10 bit and there are ways of taking your original 8 bit master and extrapolating additional grey shades from that signal through smoothing or other calculations. But the reality is that 8 bits for a 13 stop dynamic range is really not enough.

The whole reason for S-Log is to give us a way to take the 14ish stop range of a typical linear 12 bit camera sensor and squeeze as much of that signal as possible into a signal that remains useable and will pass through existing editing and post production workflows without the need for extensive processing such as de-bayering or RAW conversion. So our signal which starts at 12 bits has already been heavily processed to get it from 12 bits to 10. Going from 10 bit down to 8 is a step too far IMHO.

[Doug Jensen]

Originally Posted by Ron Aerts

Doug, do you think recording S-log 422 to an 8bit recorder has an advantage in post?

I agree with Alister and he has answered it better than I could. Thank you, Alister.

[Leonard Levy]

Alister,
Thanks for all your help with a string of question of SLog at NAB last week. I have a couple more if you're still out there as I was playing with a DSC chart and the matrix last night and looked at some of the set-ups you've proposed on the boards .
The first is still an SLog question that I asked Doug here.

- What is the point of altering SLog with the PP menus in the new firmware especially as it locks you of the LUTS? Do you think it would be possible to make a less aggressive one with more chroma to be similar to C-log and use with 8 bit? Would that be any better than a cine gamma?

- I assumed that I would look (at least to start with ) for one nice color matrix to use with all my gammas and just change the saturation sometimes to accomodate them. (You could of course go for different looks with different matrixes as well.)
I've noticed that sometimes you've often suggested one matrix set-up for a cinegamma and another quite different one say for Rec 709 or for the "faux log " profile on your site. Did you feel that different gammas wanted different color matrix settings or did it just fall out that way when you were playing around?

Thanks to everyone for your help.

[Alister Chapman]

Gamma has an effect on the saturation of the image. As the gamma curve alters the luminance of various parts of the image there is a knock on effect to how colourful the image looks as if you raise the luma without changing the matrix the ratio of colour to brightness reduces and the image looks less saturated. The reverse is also true.
So you can use one matrix and then alter the saturation to get a similar look from gamma to gamma, but it may still not look exactly the same.

Many of the looks I create are for specific applications so I often tweak the matrix, so you'll find me mixing and matching different matrix settings to different gammas quite a bit.

I don't have the new firmware yet, so I have not been able to play with it. But in theory it should be possible to create a profile similar to C-Log. But even if you do this your still dealing with a very large dynamic range and 8 bit will still be marginal. The only way your going to make a truly 8 bit friendly log profile will by reducing the dynamic range by adjusting the gamma gain. By the time you've done this, I suspect you'll end up with a curve not dissimilar to a cinegamma. There's no free lunch. If you want to record a greater dynamic range than the cinegammas offer, then realistically you need more data bits than 8.

[Ron Aerts]

Originally Posted by Alister Chapman

Going from 10 bit down to 8 is a step too far IMHO.

Thanks Allister, very clearly explained.

[Doug Jensen]

Here's a simple test shot I did this morning.

Sony PMW-F3 Picture Profile with S-LOG testing on Vimeo

Sony will soon be releasing a free firmware upgrade (v1.4) for all PMW-F3 owners. A major change for v1.4 is that every F3 will now have a gamma option called "S-LOG" that can be selected from the camera's normal Picture Profile menus.

In the past, if you wanted S-LOG on your camera, you had to purchase the CBK-RGB01 Dual Link 444RGB Upgrade. That is no longer necessary unless you also want to have 4:4:4 output capability and LUTs. You'll still need the CBK-RGB01 upgrade if you want those two features.

The purpose of these simple test shots was to see if I could create a Picture Profile that had better dynamic range that the Cine gamma settings I normally use -- but still be able to create an image that has good saturation, sharpness, and correct black levels so that grading would not be necessary. I prefer NOT to grade if I can get the look I want with a Picture Profile instead. But a little extra dymanic range would be nice.

I have included four test shots:

1) The standard, factory-default look with no Picture Profile or S-LOG is selected.

2) Ungraded S-LOG that was shot with the CBK-RGB01 Dual Link 444RGB Upgrade.

3) A Picture Profile that I call "V-LOG" that uses S-LOG for the gamma setting - PLUS several other profile adjustments to provide a pleaseing final image that will not require grading.

4) The standard Picture Profile I normally use and describe in my F3 training DVD called "Vortex-A" which uses a Cine gamma and other settings that are very different from "V-LOG".

To keep the exposure consistent, the aperture was adjusted so that the white styrofoam on the right side of the screen was hitting 90% on a leader WFM. I realize that 90% exposure for white is higher than some people would expose S-LOG, but for this test I wanted to be consistent between all four shots. None of the whites are blown out in any of the shots.

Conclusions:

As expected, the camera looks horrible when no Picture Profile is selected. Anyone who shoots without using a good PP or S-LOG is clearly not using the camera to it's full capabilities.

The normal S-LOG is mode is washed out and will require grading (that's what S-LOG is supposed to look like) but that is not my preferred workflow. I prefer not to grade if I can avoid it. However, if you prefer to grade, then you can't beat S-LOG for keeping all your options open to you in post.

I feel that the V-LOG profile I created was successful at providing better contrast and better shadows than Vortex-A with about the same amount of saturation and sharpness. Maybe too much saturation? I purposely chose a subject that had a lot of color so further testing will be needed to see how it works on faces and other subjects with less intense colors.

vortexmedia.com/DVD_F3.html

Doug

[Douglas Villalba]

It is over saturated, but that is the purpose of a grading test. It is to see how mush you can push it to see if it can hold.

[Leonard Levy]

Doug,
Thanks for the test but on first glance I can't tell too much from that image. Id lov e to see the same PP's with a someone sitting next to a window.